Aggregate photoconductive compositions and elements containing a styryl amino group containing photoconductor

ABSTRACT

An improved &#39;&#39;&#39;&#39;aggregate&#39;&#39;&#39;&#39; photoconductive composition and electrophotographic elements containing the same are prepared using from 0.1 to less than about 15 weight percent of a compound having a central carbocyclic or sulfur heterocyclic divalent aromatic ring joined to two amino-substituted styryl radicals through the vinylene groups of the styryl radicals.

United States Patent [191 Contois et a1.

[451 Mar. 25, 1197s 1 1 AGGREGATE PHOTOCONDUCTIVE COMPOSITIONS AND ELEMENTS CONTAINING A STYRYL AMINO GROUP CONTAINING PHOTOCONDUCTOR [75] Inventors: Lawrence E. Contois, Webster;

Louis ,1. Rossi, both of Rochester,

[73] Assignee: Eastman Kodak Company,

Rochester, NY.

[22] Filed: Feb. 19, 1974 [21] Appl. No.: 443,655

Related U.S. Application Data [63] Continuation-impart of Ser. No. 357,441, May 4,

1973, abandoned.

[52] U.S. Cl. 96/1.6, 96/15 [51] int. Cl G03g 5/06 [58] Field of Search ..96/1.5, 1.6

[56] References Cited UNITED STATES PATENTS 3,189,447 6/1965 Neugebauer et a1 96/l.5

Primary Examiner-Roland E. Martin, Jr. Attorney, Agent, or FirmR. P. Hilst [57] ABSTRACT 11 Claims, N0 Drawings AGGREGATE PHOTOCONDUCTIVE COMPOSITIONS AND ELEMENTS CONTAINING A STYRYL AMINO GROUP CONTAINING PHOTOCONDUCTOR This application is a continuation-in-part of U.S. Ser. No. 357,441,filed May 4, 1973, now abandoned. Cross reference is also made to copending Contois and Rossi, U.S. Ser. No. 443,657, filed concurrently herewith and entitled Photoconductive Composition and Elements Containing Same.

FIELD OF THE INVENTION This invention relates to electrophotoraphy and in particular to photoconductive compositions and elements.

DESCRIPTION OF THE PRIOR ART The process of xerography, as disclosed by Carlson in U.S. Pat. No. 2,297,691, employs an electrophotographic element comprising a support material bearing a coating of an insulating material whose electrical resistance varies with the amount of incident electromagnetic radiation it receives during an imagewise exposure. The element, commonly termed a photoconductive element, is first given a uniform surface charge, generally in the dark after a suitable period of dark adaptation. It is then exposed to a pattern of actinic radiation which has the effect of differentially reducing the potential of this surface charge in accordance with the relative energy contained in various parts of the radiation pattern. The differential surface charge or electrostatic latent image remaining on the electrophotographic element is then made visible by contacting the surface with a suitable electroscopic marking material. Such marking material or toner, whether contained in an insulating liquid or on a dry carrier, can be deposited on the exposed surface in accordance with either the charge pattern or discharge pattern as desired. Deposited marking material can then be either perma' nently fixed to the surface of the sensitive element by known means such as heat, pressure, solvent vapor or the like, or transferred to a second element to which it can similarly be fixed. Likewise, the electrostatic charge pattern can be transferred to a second element and developed there.

Various photoconductive insulating materials have been employoed in the manufacture of electrophotographic elements. For example, vapors of selenium and vapors of selenium alloys deposited on a suitable support and particles of photoconductive zinc oxide held in a resinous, film-forming binder have found wide application in present-day decument copying processes.

Since the introduction of electrophotography, a great many organic comounds have also been screened for their photoconductive properties. As a result, a very large number of organic compounds have been known to possess some degree of photoconductivity. Many organic compounds have revealed a useful level of photoconduction and have been incorporated into photoconductive compositions. Among these organic photoconductors are the triphenylamines as described in U.S. Pat. No. 3,180,730 issued Apr. 27, 1965, and other aromatic ring compounds such as those described in British Pat. No. 944,326 dated Dec. 1 l, 1963; U.S. Pat. No. 3,549,358 issued Dec. 22, 1970 and U.S. Pat. No. 3,653,887 issued Apr. 4, 1972.

Optically clear organic photoconductor-containing elements having desirable electrophotographic properties can be especially useful in electrophotography. Such electrophotographic elements can be exposed through a transparent base if desired, thereby providing flexibility in equipment design. Such compositions, when coated as a film or layer on a suitable support, also yield an element which is reusable; that is, it can be used to form subsequent images after residual toner from prior images has been removed by transfer and/or cleaning. Thus far, the selection of various compounds for incorporation into photoconductive compositions to form electrophotographic layers has proceeded on a compound-by-compound basis. Nothing as yet has been discovered from the large number of different photoconductive substances tested which permits ef fective prediction, and therefore selection of the particular compounds exhibiting the desired electrophotographic properties.

A high speed heterogeneous or aggregate multiphase photoconductive system was developed by William A. Light which overcomes many of the problems of the prior art. This aggregate photoconductive composition (as it is referred to hereinafter) is the subject matter ofU.S. Pat. No. 3,615,414 issued Oct. 26, 1971 and is also described in Gramza et al. U.S. Pat. No. 3,732,180 issued May 8, 1973. The addenda disclosed therein are responsible for the exhibition of desirable electrophotographic properties in photoconductive elements prepared therewith. In particular, they have been found to enhance the speed ofmany organic photoconductors when used therewith. The degree of such enhancement is, however, variable, depending on the particular organic photoconductor so used.

SUMMARY OF THE INVENTION In accord with the present invention there is provided an aggregate photoconductive composition containing at least two different organic photosensitive components in solid solution with the continuous phase of the multiphase aggregate composition, one of said components being a non-blue light absorbing organic photoconductor and one of said components being an amount within the range of from about 0.1 to less than about 15 weight percent based on the dry weight of said composition of a compound having a central carbocyclic or sulfur heterocyclic divalent aromatic ring joined to two amino-substituted styryl radicals through the vinylene groups of the styryl radicals.

The improved aggregate photoconductive compositions of the present invention offer a number of advantages. Among others, it has been noted that these compositions provide especially useful reusable photoconductive compositions because of their ability to resist electrical fatigue upon being subjected to a large number of repetitive electrophotographic imaging cycles.

In addition, the improved aggregate photoconductive compositions of the invention offer an unexpected enhancement in blue light sensitivity.

Moreover, it has also been found that aggregate photoconductive compositions containing the distyrylcontaining aromatic compounds used in the present invention exhibit improved temperature stability. Accordingly, the improved aggregate photoconductive compositions of the invention containing these compounds are useful over a wider range of operating temperatures.

. In addition, it has been found that the above advan tages provided by the improved aggregate photoconductive compositions of the present invention are generally obtained without any substantial deleterious affect of the totality of electrophotographic properties which cooperate to produce a useful photoconductive composition.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The term non-blue light absorbing organic photoconductor" as used herein is defined as a photoconductor which exhibits little or no light absorption in the spectral range extending from about 400 to 500 nm. Such photoconductors are typically transparent to visible light and therefore colorless; or if colored, these materials are a color other than yellow, a yellow coloration of course, indicating that blue light is being absorbed. Visible light is defined herein as radiation within the 400-700 nm. region of the spectrum.

The precise mechanism(s) occurring in the improved aggregate photoconductive compositions of the invention has not been conclusively established and therefore the present invention should not be'limited by any specific theory. However, a number of obserations have been made relating to the photoconductive compositions of the invention and are presented herein to provide a better understanding of the invention.

In the first place, the photoconductive mechanism(s) which is believed to occur in the improved aggregate photoconductive compositions of the invention is considered to be different than that which normally occurs in conventional homogeneus organic photoconductive compositions. Such homogeneous compositions consist of an organic photoconductor such as a triphenylamine compound in solid solution with a polymeric binder. Typically, a sensitizer is also present in the composition. Photoconduction is believed to occur in a uniformly electrostatically charged homogeneous photoconductive composition as a result to exposure to radiation of the type to which the organic photoconductor is intrinsically sensitive (or to which the organic photoconductor is made sensitive by the addition of a sensitizer), thereby causing the generation of charge carriers within the organic photoconductor. These charge carriers are then transported through the photoconductive composition to a conductive layer where they are dissipated.

In the improved aggregate photoconductive compositions of the present invention charge carriers are believed to be generated in the photoconductive composition from within the particles of aggregate material contained therein. these particles of aggregate material are generally composed of a cocrystalline complex of an organic sensitizing dye, such as a pyrylium type dye, and a polymeric material, such as a polycarbonate, and are visible within the photoconductive composition with the aid ofa microscope. These aggregate particles are thus dispersed as a discontinuous phase in the photoconductive composition and are not in a solid solution with the remainder of the composition. (Further detail relating to the preparation and composition of these aggrergate particles is set forth hereinafter.)

in accord with the invention one or more non-blue light absorbing organic photoconductor(s) is incorporated in solid solution with the continuous phase of the aggregate photoconductive composition of the invention. These materials may aid the above-described aggregate particles in the formation of charge carriers, and it is also believed that the organic photoconductor(s) plays a primary role in the transport of the charge carriers through the aggregate photoconductive composition. It has been shown, for example, that the photoconductivity, i.e. electrophotographic speed, of the compositions of the invention when exposed to a white light source is significantly increased by the addition of the organic photoconductor(s). Without the incorporation of one or more organic photoconductors, the white light speed of the composition is so low that the compositions of the present invention are unacceptable for use in conventional office copier applications.

The distyryl-containing aromatic compound contained in the aggregate photoconductive composition of the invention is used as a fatigue reducer" and as a temperature stabilizer." For example, the improved aggregate composition of the invention exhibit substantial improvement in resistance to electrical fatigue even when subjected to a large number of repetitive imaging cycles at relatively high ambient temperature conditions. ln addition, although these distyryl-containing aromatic compounds are known to possess photoconductive properties (as described in the crossreferenced Contois and Rossi US. patent application Ser, No. 443,657, entitled Photoconductive Composition and Elements Containing Same filed concurrently herewith), these compounds are believed to act as a blue light sensitizer in the compositions of the present invention. That is, these compounds appear to absorb blue light and then, through some type of chemical, electronic or combined chemicalelectronic mechanism, intimately interest with the aggregate particles to generate charge carriers.

The precise reason(s) that the distyryl-containing ar omatic compounds act as a blue sensitizer in the photoconductive composition of the invention are not completely understood. Although these distyryl-containing compounds do possess photoconductive properties and exhibit blue light absorption, these factors alone do not account for the enhanced blue sensitivity of the aggregate photoconductive compositions of the invention. This is readily demonstrated by the fact that certain known nitrosubstituted triphenylamine photoconductors which also exhibit blue light absorption, such as compounds similar to the nitrosubstituted triarylamines shown in US. Pat. No. 3,180,730, do not provide the above-described blue sensitization effect when substituted for the distyryl-containing compounds incorporated in the photoconductive compositions of the invention.

Similarly, the precise reason(s) that the distyrylcontaining aromataic compounds improve the temperature stability and act as a fatigue reducer in the aggregate photoconductor composition of the invention is also not fully understood. However, here again it is known that molecularly much simpler nitro-substituted triphenylamine photoconductive compounds similar to those shown in US. Pat. No. 3,180,730 do not provide these advantages when substituted for the distyrylcontaining aromatic compounds used in the aggregatecontaining photoconductive compositions of the type described above.

The preferred distyryl-containing aromatic compounds used in the invention may be characterized by the following formula:

l -CH=CH-Ar wherein R R R and R which can be the same or different, represent alkyl or aryl radicals including substituted alkyl and aryl radicals;

Ar, and Ar which can be the same or different, represent an unsubstituted or a substituted phenyl radical having one or more substituents selected from the group consisting of an alkyl, aryl, alkoxy, aryloxy, and halogen substituent; and

Ar represents a carbocylic or sulfur heterocyclic,

mononuclear or polynuclear, aromatic ring typically containing 4 to 14 carbon atoms in the ring such as phenyl, naphthyl and anthryl aromatic groups as well as substituted aromatic groups having one or more substituents selected from the group of substituents defined above as substituents for Ar and Ar Typically, R R R and R. represent one of the following alkyl or aryl groups:

1. an alkyl group having one to l8 carbon atoms e.g., methyl, ethyl, propyl, butyl, isobutyl, octyl, dodecyl, etc. including a substituted alkyl group having one to 18 carbon atoms such as a. alkoxyalkyl e.g., ethoxypropyl, methoxybutyl, propoxymethyl, etc.,

b. aryloxyalkyl e.g., phenoxyethyl, naphthoxymethyl,

phenoxypentyl, etc.

0. aminoalkyl, e.g., aminobutyl, aminoethyl, aminopropyl, etc., d. hydroxyalkyl e.g., hydroxypropyl, hydroxyoctyl,

etc.,

e. aralkyl e.g., benzyl, phenethyl, etc.

f. alkylaminoalkyl e.g., methylaminopropyl, methylaminoethyl, etc., and also including dialkylaminoalkyl e.g., diethylaminoethyl, dimethylaminopropyl, propylaminooctyl, etc.,

g. arylaminoalkyl, e.g., phenylaminoalkyl, di-

phenylaminoalkyl, N-phenyl-N-ethylaminopentyl, N-phenyl-N-ethylaminohexyl, naphthylaminomethyl, etc.,

h. nitroalkyl, e.g., nitrobutyl, nitroethyl, nitropentyl,

etc.,

i. cyanoalkyl. e.g., cyanopropyl, cyanobutyl, cyanoethyl, etc., and

j. haloalkyl, e.g., chloromethyl, bromopenetyl, chlorooctyl, etc.,

k. alkyl substituted with an acyl group having the formula wherein R is hydroxy, hydrogen, aryl, e.g., phenyl, naphthyl, etc., lower alkyl having one to eight carbon atoms e.g., methyl, ethyl, propyl, etc., amino including substituted amino, e.g., diloweralkylamino, lower alkoxy having one to eight carbon atoms, e.g., butoxy, methoxy, etc., aryloxy, e.g., phenoxy, naphthoxy, etc;

2. an aryl group, e.g., phenyl, naphthyl, anthryl, fluoroenyl, etc., including a substituted aryl group such as a. alkoxyaryl, e.g., ethoxyphenyl, methoxyphenyl,

propoxynaphthyl, etc.

b. aryloxyaryl, e.g., phenoxyphenyl, phenoxynaphthyl, etc.

c. aminoaryl, e.g. aminophenyl, aminonaphthyl, aminoanthryl, etc.

d. hydroxyaryl, e.g., hydroxyphenyl, hydroxynaphthyl,

e. biphenylyl,

f. alkylaminoaryl, e.g., methylaminophenyl, me-

thylaminonaphthyl, etc. and also including dialkylaminoaryl, e.g., diethylaminophenyl, di propylaminophenyl etc.

g. arylaminoaryl, e.g., phenylaminophenyl, diphenylaminophenyl, N-phenyl-N- etehylaminophenyl, naphthylaminophenyl, etc.

h. nitroaryl e.g., nitrophenyl, nitronaphthyl, ni-

troanthryl, etc.,

i. cyanoaryl, e.g., cyanophenyl, cyanonaphthyl, cyanoanthryl, etc.,

j. haloaryl, e.g., chlorophenyl, bromophenyl, chloroanphthyl, etc.,

k. alkaryl, e.g., tolyl, ethylphenyl, propylnaphthyl,

etc., and l. aryl substituted with an acyl group having the formula wherein R is hydroxy, hydrogen aryl, e.g., phenyl, naphthyl, etc., amino including amino, e.g., diloweralkylamino, lower alkoxy having one to eight carbon atoms, e.g., butoxy, methoxy, etc., aryloxy, e.g., phenoxy, naphthoxy, etc., lower alkyl having one to eight carbon atoms, e.g., methyl, ethyl, propyl, butyl, etc.

Typically, when either Ar or Ar represent a substituted phenyl radical the substituents on the phenyl radical are alkyl or aryl groups as defined above for R,, R R R or also any of the following:

1. an alkoxy group having one to 18 carbon atoms. e.g.,

methoxy, ethoxy, propoxy, butoxy, etc.,

2. an aryloxy group e.g., phenoxy, naphthoxy. etc.: and

3. halogen such as chlorine, bromine, fluorine or iodine.

Typical compounds which belong to the general class of distyryl-containing aromatic compounds described 7 8 herein include the following materials listed in Table l resistance to electricall fatigue and improved temperabelow: ture stability TAB LE 1 Melting Point DC (I) l-Dipnenyla::;inol' l-diphenylamino) styryl ]stilbene having the formula 209-211 (II) l-Di-(p-tolyla zinoyw-[Lt-( diptolylamino)styryl ]sti1bene having the styryl]stilbene having the formula 1o6-1o8 (IV) l-Di-(p-tolylarzino)2'-[H-(di-ptolylamino)styryl ]stilbene having the crrula CH=CH N(pCH C H CH=CH I l(pCH C H v -(p-colylmino)-2 i alimeth fl i-(ai- -tdi latmino st r l1stilbene 211-215" having the formula i CH3 i CE=CH -N(p-CH3C H L'- .7 cn C. It(p ca c (V1) 9,lO-BisPl-(dipy )styr-yl ]-anthracene having the formula 288290 (VIII) awn-206 Compounds which below to the general class of disty- The aggregate compositions used in this invention ryl-containing aromatic compounds described herein comprise an organic sensitizing dye and an electrically and which are preferred for use in accord with the presinsulating, film-forming polymeric material They may ent invention include those compounds having the be prepared by several techniques, such as. for examstructural formula shown above wherein Ar Ar: and ple the so-called dye first" technique described in Ar are unsubstituted phenyl radicals or alkyl substi- Gramza et. al., US. Pat. No. 3,615,396 issued Oct. 26. tuted phenyl radicals having no more than two alkyl 1971. Alternatively, they may be prepared by the sosubstituents said alkyl substituents containing 1 or 2 called "shearing" method described in Gramza. UAS. carbon atomsThese compounds are preferred because Pat. No. 3,615,415 issued Oct. 26, 1971. this latter aggregate compositions containing the same exhibit in- 65 th d i l h hi h pged h i f rh h w creased blue sensitivity and may also exhibit improved conductive composition prior to coating and thus climinates subsequent solvent treatment, as was disclosed in Light, US. Pat. No. 3,615,414 referred to above. By whatever method prepared, the aggregate composition Particularly useful dyes in forming the feature aggregates are pyrylium dye salts having the formula:

is combined with the above-described distyryl- R containing compounds and one or more organic photo- 7 conductors in a suitable solvent to form an organic photoconductor-containing composition which is G) coated on a suitable support to form a separately identifiable multiphase composition, the heterogeneous na- R X R Z ture of which is generally apparent when view under 10 5 6 magnification, although such compositions may appear to be substantially optically clear to the naked eye in wherein:

the absence of magnification. There can, of course, be R and R can each be phenyl radicals, including submacroscopic heterogeneity. suitably, the dyestituted phenyl radicals having at least one substitucontaining aggregate in the discontinuous phase is preent chosen from alkyl radicals of from 1 to about dominantly in the size range of from about 0.01 to 6 carbon atoms and alkoxy radicals having from 1 about 25 microns. to about 6 carbon atoms;

In general, the aggregate compositions formed as de- R can be alkylamino-substituted phenyl radical havscribed herein are multiphase oroganic solids containing from 1 to 6 carbon atoms in the alkyl moiety, ing dye and polymer. The polymer forms an amorphous and including dialkylamino-substituted and matarix or continuous phase which contains a discrete haloalkylamino-substituted phenyl radicals; discontinuous phase as distinguished from a solution. X can abe an oxygen or a sulfer atom; and The discontinuous phase is the aggregate species which Z is an anion. is a co-crystalline complex comprised of dye and poly- The polymers useful in forming the aggregate compomer, sitions include a variety of materials. Particularly useful The term co-crystalline complex as used herein has are electrically insulating, film-forming polymers havreference to a crystalline compound which contains ing an a'lkylidene diarylene moiety in a recurring unit dye and polymer molecules co-crystallized in a single such as those linear polymers, including copolymers. crystalline structure to form a regular array of the molcontaining the following moiety in a recurring unit: ecules in a three-dimensional pattern.

Another feature characteristic of the aggregate compositions formed as described herein is that the wave- R R R length of the radiation absorption maximum character- I 8 I ll istic of such compositions is substantially shifted from A l\ the wavelength ofthe radiation absorption maximum of C .1

a substantially homogeneous dye-polymer solid solul tion formed of similar constituents. The new absorption maximum characteristic of the aggregates formed by this method is not necessarily an overall maximum for this system as this will depend upon the relative amount 40 wherein:

of dye in the aggregate. Such an absorption maximum R and R when taken separately. can each be a hyshift in the formation of aggregate systems for the presdrogen atom, an alkyl radical having from one to ent invention is generally of the magnitude of at least about 10 carbon atoms such as methyl, ethyl, isoabout 10 nm. lf mixtures of dyes are used, one dye my butyl, hexyl, heptyl, octyl, nonyl, decyl and the like cause an absorption maximum shift to a long waveincluding substituted alkyl radicals such as trifluolength and another dye cause an absorption maximum romethyl, etc., and an aryl radical such as phenyl shift to a shorter wavelength. In such cases, a formation and naphthyl, including substituted aryl radicals of the aggregate compositions can more easily be having such substituents as a halogen atom, an identified by viewing under magnification. '7 alkyl radical of from 1 to about 5 carbon atoms,

Sensistizing dyes and electrically insulating polyetc.; and R and R when taken together, can repmeric materials are used in forming these aggregate resent the carbon atoms necessary to complete a compositions. Typically, pyrylium dyes, including pysaturated cyclic hydrogen radical including cyclorylium, bispyrylium, thiapyrylium and selenapyrylium alkanes such as cyclohexyl and polycycloalkanes dye salts and also salts of pyrylium compounds contain- Such as norbornyl, the total number of carbon ing condensed ring systems such as salts of benatoms in R and Rm being up to about 19; zopyrylium and naphthopyrylium dyes are useful in R8 and 11 n each be hydrogen, an alkyl radical of forming such compositions. Dyes from these classes from 1 to about 5 carbon atoms, e.g., or a halogen which may be useful are disclosed in Light US. Pat. such as chloro, bromo, iodo, etc.; and No. 3,615,414. R is a divalent radical selected from the following:

wherein:

each R is a phenylene radical including halo substituted phenylene radicals and alkyl substituted phenylene radicals; and R and R are as described above. Such compositions are disclosed, for example in U.S. Pat. Nos. 3,028,365 and 3,317,466. Preferably polycarbonates containing an alkylidene diarylene moiety in the recurring unit such as those prepared with Bisphenol A and including polymeric products of ester exchange between diphenylcarbonate and 2,2-bis-(4-hydroxyphenyl)- propane are useful in the practice of this invention. Such compositions are disclosed in the following U.S. Pat. Nos. 2,999,750 by Miller et al., issued Sept. 12, l96l 3 8,874 byLaakso et al., issued June 12, 1962; 3,038,879 by Laakso et al., issued June 12, 1962; 3,038,880 by Laakso et al., issued June 12, 1962; 3,106,444 by Laakso et al., issued Oct. 8, 1963; 3,106,545 by Laakso et al., issued Oct. 8, 1963; and 3,106,546 by Laakso et al., issued Oct. 8, 1963. A wide range of film-forming polycarbonate resins are useful, with completely satisfactory results being obtained when using commercial polymeric materials which are characterized by an inherent viscosity of about 0.5 to about 1.8.

The following polymers are included among the materials useful in the practicie of this invention:

Table 2 Polymeric Material 1 poly(4,4'-isopropylidenediphenylene-col ,4-cyclohexanylenedimethylene carbonate) poly(ethylenedioxy-3,3'-phenylene thiocarbonate) 3 poly(4,4-isopropylidenediphenylene carbonate-co-terephthalate) poly( 4,4-isopropylidenediphenylene carbonate) 5 poly(4,4-isopropylidenediphenylene thiocarbonate) poly(4,4-secbutylidenediphenylene carbonate) poly(4.4'-isopropylidenediphenylene carbonate-block-oxyethylene) poly(4,4'-isogropylidenediphenylene carbonateloc '-oxytetramet ylene) polyl4,4' isopropylidenebis(Z-methylphenylenej-carbonate] poly(4,4"isopropylidenediphenylene-col ,4-phenylene carbonate) poly(4,4'-isopropylidenediphenylene-co- 1.3-phenylene carbonate) poly(4,4-isopropylidenediphcnylene-co- 4,4'-diphenylene carbonate) poly-(4,4-isopropylidenediphenylene-co- 4,4'oxydiphenylene carbonate) poly(4.4' isoprocsaylidenediphenylene-co- 4,4'-carbonyl iphenylene carbonate) poly(4,4'-isopropylidenediphenylene-co- 4,4-ethylenediphenylene carbonate) poly]4,4'-methylenebis(Z-methylphenylene )carbonate] poly] l.l-(p-bromophenylethylidene )bis( I ,4-

phenylene )carbon ate l H...--Ia v2 sa as.

No. Polymeric Material 18 poly]4,4'-isopropylidenediphenylene-co- 4,4'-sulfonyldiphenylene) carbonate] l9 po1y[4,4'-cyclohexanylidene(4-diphenylene) carbonate] 20 poly] 4,4'-isopropylidenebis( 2-chlorophenylene) carbonate] 21 poly( 4,4'-hexafluoroisopropylidenediphenylene carbonate) 22 poly(4,4'-isopropylidenediphenylene 4,4-

isopropylidenedibenzoate) 23 poly(4,4'-isoprop lidenedibenzyl 4,4-

isopro ylidene ibenzoate) 24 poly[4,4 l,Z-dimethylpropylidene)diphenylene carbonate] 25 poly[4,4'-( l,2,2-trimethylpropylidene diphenylene carbonate] 26 poly 4,4'-] l-(a-naphthyl)ethylideneh diphenylene carbonate 27 poly[4,4'-( l,3-dimethylbutylidene)- diphenylene carbonate] 28 poly[ 4.4-( Z-norbornylidene )diphenylene carbonate] I 29 poly] 4.4'-( hexahydro-4.7-methanoindan-5- ylidene) diphenylene carbonate] Electrophotographic elements of the invention conthe spectral sensitivity or electrophotosensitivity of the element can be added to the composition of the element when it is desirable to produce the characteristic effect of such materials. If desired, other polyers can be incorporated in the vehicle, for example, to physical properties such as adhesion of the photoconductive layer to the support and the like. A list of various other polyers which may be used may be found in the publicaton Research Disclosure, Vol. No. 109, May, 1973, p. 63, in Paraphgram [V B of the article entitled Elec trophotographic elements, materials, and processes". The foregoing article is hereby incorporated herein by reference thereto. Techniques for the preparation of aggregate photoconductive layers containing such additional vehicles are described in C. L. Stephens, U.S. Pat. No. 3,679,407, issued July 25, 1972, and entitled METHOD OF FORMlNG HETEROGENEOUS PHO- TOCONDUCTIVE COMPOSlTlONS AND ELE- MENTS. The photoconductive layer of the invention can also be further sensitized by the addition of effective amounts of other known sensitizing compounds to exhibit improved electrophotosensitivity.

In accord with the invention, the above-described distyryl-containing aromatic compounds are combined with one or more non-blue light-absorbing organic photoeonductors to form the improved aggregate photoconductive compositions of the invention. The nonblue light absorbing organic photoconductive materials are advantageously incorporated by dissolving these materials in the organic solvent dope used in coating the improved aggregate photoconductive compositions of the invention. As a result these organic photoconductive materials are in solid solution with the continuous polymer phase of the multiphase structure of the resultant aggregate photoconductive composition. In-

corporation of these organic photoconductors in the' electrical speed of the aggregate composition. W

Especially useful organic photoconductors which exhibit little or no blue light absorption and which may be incorporated in the improved aggregate compositions of the invention include non-blue light absorbing materials selected from the following classes of photoconductors: Arylamine photoconductors including substi' tuted and unsubstituted arylamines, diarylamines, nonpolymeric triarylamines and polymeric triarylamines such as those described in Fox, U.S. Pat. No. 3,240,597, issued Mar. 15, 1966 and Klupfel et al. U.S. Pat. No. 3,180,730 issued Apr. 27, 1965; and polyarylalkane photoconductors of the types described in Noe et a1. U.S. Pat. No. 3,274,000, issued Sept. 20, 1966, Wilson, U.S. Pat. No. 3,542,547, issued Nov. 24, 1970; Seus et a1. U.S. Pat. No. 3,542,544, issued Nov. 24, 1970; and in Rule U.S. Pat. No. 3,615,402, issued Oct. 26, 1971. Of course, if desired, other non-blue light absorbing organic photoconductors such as those selected from the various classes of organic photoconductors disclosed in Light, U.S. Pat. No. 3,615,414 (hereby incorporated herein by reference thereto) may also be incorporated in the aggregate compositions of the invention.

The amount of the above-described distyrylcontaining compound incorporated into the aggregate photoconductive compositions and elements of the invention should be less than about 15 weight percent based on the total dry weight of the resultant aggregate photoconductive compositions.

Particularly useful results are obtained where the aggregate compositions of the invention contains 15 to about 40 percent by weight of one or more non-blue light absorbing organic photoconductors and as an additive an amount of the distyryl-containing aromatic compound within the range of from about 0.1 to about weight percent based on the total dry weight of the resultant composition. As the amount of the distyrylcontaining aromatic compound is increased beyond the weight percent level specified herein, the absorportion and photoconductive properties of the compound "bgin'tsfiave a substantial effect on the resultant photoconductive composition. in addition, the enhancement in electrical fatigue resistance (sometimes referred to in the-art as charge regeneration) provided in the present invention by use of a relatively small amount of the distyryl-containing compound is impared as very large amounts of the distyryl-containing aromatic compound are usecd (i.e. amounts on the order of about 25 weight percent or more). It has been found that certain especially useful embodiments of the present invention which contain in solid solution with the continuous phase of the aggregate photoconductive composition (a) 25 weight percent or more of one or more non-blue light absorbing organic photoconductors and (b) less than 15 weight percent, preferably 5 to 10 weight percent, of the distyryl-containing aromatic compounds described herein provide optimum reusable characteristics. That is, the small amount of the distyryl compound appears to function primarily as a fatigue reducer, temperature stabilizer, and blue light sensitizer for the particulate co-crystalline complex incorporated in the aggregate photocoductive composition as described previously herein and appears to have little or no deleterious effect on the photoresponse of the composition to visible light outside the blue region, i.e., light having a wavelength of from 500 to 700 nm.

As noted above, the amounts of the non-blue light absorbing organic photoconductors incorporated in the compositions of the invention which produce optimum results in the terms of electrical fatigue, speed, and temperature stability are usually within the range of from about 15 to about 40, preferably 25 to about 40, percent by weight based on the total dry weight of the resultant aggregate photoconductive composition. However, larger and somewhat smaller amounts of thgsltotoconductors may also be used Suitable supporting materials on which the aggregate photoconductive layers of this invention can be coated include any of a wide variety of electrically conducting supports for example, paper (at a relative humidity above 20 percent); aluminum-paper laminates; metal foils such as aluminum foil, zinc foil, etc; metal plates, such as aluminum, copper, zinc, brass and galvanized plates; vapor deposited metal layers such as silver, nickel, aluminum and the like coated on paper or conventional photographic film bases such as cellulose acetate, polystyrene, etc. Such conducting materials as nickel can be vacuum deposited on transparent film supports in sufficiently thin layers to allow electrophotographic elements prepared therewith to be exposed from either side of such elements. An especially useful conducting support can be prepared by coating a support material such as poly(ethylene terephthalate) with a conducting layer containing a semiconductor dispersed in a resin or vacuum deposited on the support. Such conducting layers both with and without insulating barrier layers are described in U.S. Pat. No. 3,245,833 by Trevoy, issued Apr. 12, 1966. Likewise, a suitable conducting coating can be prepared from the sodium salt of a carboxyester lactone of maleic anhydride and a vinyl acetate polymer. Such kinds of conducting layers and methods for their optimum preparation and use are disclosed in U.S. Pat. Nos. 3,007,901 by Minsk, issued Nov. 7, 1961 and 3,262,807 by Sterman et al., issued July 26, 1966 Coating thickness of the photoconductive composition on the support can vary widely. Normally, a coating in the range of about 10 microns to about 300 mi crons before drying is useful for the practice of this invention. The preferred range of coating thickness is found to be in the range from about 50 microns to about microns before drying, although useful re sults can be obtained outside of this range. The resultant dry thickness of the coating is preferably between about 2 microns and about 50 microns, although useful results can be obtained with a dry coating thickness be- 1W9IL Q1192! 132d. b QLZQQ micron After the photoconductive elements prepared according to the method of this invention have been dried, they can be employed in any of the well-known electrophotographic processes which require photoconductive layers. One such process is the xerographic process. In a process of this type, an electrophotographic element is held in the dark and given a blanket electrostatic charge by placing it under a corona discharge. This uniform charge is retained by the layer because of the substantial dark insulating property of the layer, i.e., the low conductivity of the layer in the dark. The electrostatic charge formed on the surface of the photoconductive layer is then selectively dissipated from the surface of the layer by imagewise exposure to light by means of a conventional exposure operation such as, for example, a contactprinting technique,

or by lens projection of an image, and the like, to thereby form a latent electrostatic image in the photoconductive layer. Exposing the surface in this manner forms a pattern of electrostatic charge by virtue of the fact that light energy striking the photoconductor causes the electrostatic charge in the light struck areas to be conducted away from the surface in proportion to the intensity of the illumination in a particular area.

The charge pattern produced by exposure is then developed or transferred to another surface and developed there, i.e., either the charge or uncharged areas rendered visible, by treatment with a medium comprising electrostatically responsive particles having optical density. The developing electrostatically responsive particles can be in the form of a dust, i.e., powder, or a pigment in a resinous carrier, i.e., toner. A preferred method of applying such toner to a latent electrostatic image for solid area development is by the use of a magnetic brush. Methods of forming and using a magnetic brush toner applicator are described in the following U.S. Pat. Nos: 2,786,439 by Young, issued Mar. 26, 1957; 2,786,440 by Giaimo, issued Mar. 26, 1957; 2,786,441 by Young, issued Mar. 26, 1957; 2,874,063 by Greig, issed Feb. 17, 1959. Liquid development of the latent electrostatic image may also be used. In liquid development, the developing particles are carried to the image-bearing surface in an electrically insulating liquid carrier. Methods of development of this type are widely known and have been described in the patent literature, for example, U.S. Pat. No.

developing processes, the most widely used method of obtaining a permanent record is achieved by selecting t a developing particle which has as one of its components a low-melting resin. Heating the powder image then causes the resin to melt or fuse into or on the element. The powder is, therefore, caused to adhere permanently to the surface of the photoconductive layer. In other cases, a transfer of the electrostatic charge image formed on the photoconductive layer can be made to a second support such as paper which would then become the final print after development and fusing. Techniques of the type indicated are well known in the art and have been described in the literature such as in RCA Review Vol. 15 (1954) pages 469-484.

The following examples are included for a further understanding of this invention.

Preparation of Distyryl-Containing Aromatic Compounds This distytyl-containing aromatic compounds used in the compositions of the invention may be prepared by known methods of chemical synthesis. Specifically, the compounds used herein are prepared by reacting any of various dialkylarylphosphonates with an appropriate aldehyde in the presence of a strong base to give the desired olefin product. By this procedure, the reaction of p-diphenylaminobenzaldehyde or 4-di-(p-tolylamino)- benzaldehyde with an appropriate bis-phosphonate and two equivalents of sodium methoxide in dimethylformamide solution is used to prepare the distyryl compounds l-Vlll listed in Table l hereinbefore.

For purposes of illustration the specific reaction procedure used to prepare compound V of Table l is as follows:

To a solution of 6.1 g of tetraethyl 4,6-dimethyl-mxylylenediphosphonate and 2.0 g. of sodium methoxide 16 in501ml of dimethylformamide isadded dropwise at room temperature 9.0 g of 4-di p- EXAMPLE 1 Using aggregate formulation methods as described earlier herein, a series of aggregate organic photoconductive compositions are prepared containing two different organic photoconductors. The basic dry formulation of each aggregate photocoductive composition tested is as follows: Bisphenol A polycarbonate (56% by weight) purchased from General Electric Co.) total amount of organic photoconductor (40-30% by weight) total amount of 4-di-p-tolylamino-4'l4-di-ptolylaminostyryll-stilbene (0-10 7c by weight) 4-(4- dimethylaminophenyl-2,6-diphenyl thiapyrylium fluoroborate (3.4% by wt.) 4-(4-dimethylaminophenyl)- 2-(4-ethoxyphenyl)-6-phenyl thiapyrylium fluoroborate (.6% by wt.). Each aggregate composition is prepared as follows:

4-(4-Dimethylaminophenyl)-2,6-diphenyl thiapyrylium fluoroborate (0.17 g) and 4-( 4- dimethylaminophenyl)-2-(4-ethoxyphenyl)-6-phenyl thiapyrylium fluoroborate (0.03 g) are dissolved in 15 mls. of dichloromethane. Three grams of bisphenol A polycarbonate are then dissolved in this solution and to this dope is added 2.0 grams (total) of organic photoconductor and 4-di-p-tolylamino-4'-[4-di-ptolylaminostyryl]-stilbene. After allowing the dope to stand overnight 12.5 mls. of dichloromethane is added and the resulting dope is hand coated on a nickel coated conductive support to obtain a dry coating thickness of 9a. Significant increases especially in blue speeds are observed when 4-di-p-tolylamino-4-[4-di-ptolylaminostyryl]-stilbene is combined with conventional organic photoconductors as shown in Table 3.

ln this example of the present application Relative H & D Electrical Speeds are reported. The relative H & D electrical speeds measure the speed of a given photoconductive material relative to other materials typically within the same test group of materials. The relative speed values are not absolute speed values. However, relative speed values are related to absolute speed values. The relative electrical speed (shoulder or toe speed) is obtained simply by arbitrarily assigning a value, R0, to one particular absolute shoulder or toe speed of one particular photoconductive material. The relative shoulder or toe speed, Rn, of any other photoconductive material, n, relative to this value, R0, may then be calculated as follows: Rn, (A,,)(R0/A0) wherein An is the absolute electrical speed of material n, R0 is the speed value arbitrarily assigned to the first material, and A0 is the absolute electrical speed of the first material. The absolute H & D electrical speed, either the shoulder (SH) or toe speed, of a material may be determined as follows: The material is electrostatically charged under, for example, a corona source until the surface potential, as measured by an electrometer probe, reaches some suitable initial value V typically about 600 volts. The charged element is then exposed to 3000K tungsten light source through a stepped density gray scale. The exposure causes reduction of the surface potential of the element under each step of the gray scale from its initial potential V to some lower potential V the exact value of which depends upon the amount of exposure in meter-candle-seconds received by the area. The results of these measurements are then plotted on a graph of surface potential V vs. log exposure for each step, thereby forming an electrical characteristic curve. The electrical or electrophotographic speed of the photoconductive composition can then be expressed in terms of the reciprocal of the exposure required to reduce the surface potential to any fixed selected value. The actual positive or negative shoulder speed is the numerical expression of divided by the exposure in meter-candle-seconds required to reduce the initial surface potential V to some value equal to V minus 100. This is referred to as the 100 volt shoulder speed. Sometimes it is desirable to determine the 50 volt shoulder speed and, in that instance, the exposure used is that required to reduce the surface potential to V,, minus 50. Similarly. the actual positive or negative toe speed is the numerical expression of 10 divided by the exposure in meter-candle-seconds required to reduce the initial potential V to an absolute value of 100 volts. Again, if one wishes to determine the 50 volt toe speed, one merely uses the exposure required to reduce V to an absolute value of 50 volts. An apparatus useful for determining the eletrophotographic speeds of photoconductive compositions is described in Robinson et al., U.S. Pat. No. 3,449,658, issued .lune 10, 1969.

TABLE 3 Each of the three films tested is identical except for the particular aggregate photoconductive composition used in each film. Each of the aggregate photoconductive compositions of the three films contains a particuate co-crystalline complex of a thiapyrylium dye and Lexan polycarbonate as a discontinuous phase dispersed in a continuous polymer phase composed of Lexan polycarbonate. The particular thiapyrylium dye used in each of the three films is 2.6-diphenyl-4-(pdimethylaminophenyl) thiapyrylium fluoroborate and the total amount of dye contained in each composition is 3% by weight based on the total dry weight of the aggregate photoconductive composition used in each film. The total amount of Lexan polycarbonate contained in each of the photoconductive compositions used in the films is 57% by weight.

A. The remaining 40% by weight of the aggregate photoconductive composition of Film No. 1 (which is a control outside the scope of the present invention) is composed entirely of the organic photoconductor 4,- 4bis-diethylaminotetraphenylmethane (TPM) which is in solid solution with the Lexan polycarbonate contained in the continuous phase of the phtotconductive composition of Film No. l.

B. The remaining 40% of the aggregate photoconductive composition of Film No. 2 (which is within the scope of the present invention) is composed of 30% by weight of TPM and 10% by weight of compound II of Table l of the present application as an additive. The TPM and compound ll used in Film No. 2 is in solid solution with the Lexan polycarbonate contained in the continuous phase of the photoconductive composition of Film No. 2.

C. The remaining 40% of the aggregate photoconduc- Weight percent of 4-di'p-tolylamino- Relative 100 Volt Toe Speeds 4'-[4-di-p-tolyl- Tungsten Blue aminostyryll-stilbene Light Source Light Source 0 40 l00* l00* 5 I 121 200 I0 30 l36(Vo=-490) 200 Weight percent of Weight percent of 4-di-p-tolylamino- (Bisl4-diethylamino] 4-[4-di-p-tolyltetraphenylmethane) aminostyryllstilbene *arhitrarily assigned a speed value of l00 within each column and within each series.

EXAMPLE 2 Three transparent photoconductive films containing aggregate photoconductive compositions are prepared similar to certain of the films of Example 1. The electrophotographic sensitivity of these films (evaluated as the inverse sensitivity of the exposure required to discharge the tilm from 500 v. to 100 v.) is determined as a function of wavelength for all electrophotographic modest positive and negative surface charging and front and rear exposure. In addition, absorption spectra for each of the three films is recorded and evaluated.

The absorption spectra of Film Nos. l-3 reveals that Film No. 1 possesses a window to blue light, i.e., visible light having a wavelength of from about 400-500 nm. That is, Film No. l exhibits very little absorption of blue light. Film No. 1, however, readily absorbs visible light having a wavelength within the spectral range of from about 500-700 nm. Film Nos. 2 and 3 exhibit an absorption spectra similar to Film No. l with respect to visible light having a wavelength within the spectral range of from about 500-700 nm. However, in contrast to Film No. 1, Film Nos. 2 and 3 also absorb blue light so that the blue window" of Film No. 1 does not appear in either Film No. 2 or 3.

The electrophotographic sensitivity of each of Film Nos. 1-3 reveals that both controls, i.e., Film Nos. 1 and 3, exhibit rather poor electrophotographic sensitivity when exposed to blue light but exhibit good and substantially similar electrophotographic sensitivity to visible light having a wavelength extending from about 500-700 nm. Film No.2 ofthe present invention, however, exhibits good eleetrophotographic sensitivity to blue light. Film No. 2 also exhibits good electrophotographic sensitivity to light having a wavelength extending from about 500-700 nm. Except for the increased electrophotographic sensitivity to blue light exhibited by Film No. 2 of the present invention, the electrophotographie sensitivity of Film Nos. l-3 to light having a wavelength within the range of from 500-700 nm is quite similar.

The results of the tests shown in this example indicate that the blue sensitization capability of aggregate photoconductive compositions containing compound II of Table l (which is representative of the distyrylcontaining aromatic compounds of the present invention) is a unique effect and cannot be obtained simply by substituting other known blue absorbing organic photoconductors, such as DTN, for compound 11.

Of perhaps even greater significances are the additional test findings that when temperature stability and electrical fatique tests are run on Film Nos. l-3, the results show that Film No. 2 (which contains as an additive one ofthe distyryl-containing aromatic compounds used in the present invention) exhibits substantially better resistance to electrical fatique and substantially better temperature than either Film No. l or 3. For example, Film No. 2 appears to provide good reusable electrophotographic imaging characteristics similar to room temperature (i.e. about 28C) imaging characteristics up to temperatures approaching 6570C. In contrast, the electrophotographic imaging characterisics of Film Nos. 1 and 3 begins to fall off quite noticeably at a temperature of about 55C in comparison to the normal room temperature (about 28C) imaging characteristics provided by these same films.

EXAMPLE 3 To further illustrate certain of the preferred aggregate photoconductive compositions of the present invention, a 500 cycle electrical regeneration test and an evaluation of relative white light speed is performed on a series of three aggregate photoconductive elements to determine optimum amounts of the distyrylcontaining aromatic compound to be incorporated therein for use as an additive. These elements are prepared having coated thereon an aggregate photoconductive composition containing the following materials expressed in weight precent; Bisphenol A polycarbonate (56%) purchased from General Electric Co. under the trademark Lexan 4-(4-dimethylaminophenyl)- 2,6-diphenyl thiapyrylium hexafluorophosphate sensitizing dye salt (4%); and the remaining 40% of each composition is as shown in Table 4. Each of the three aggregate photoconductive elements is prepared by coating the above-described aggregate composition on a conductive film support to obtain a dry coating thickness of about 9 microns. The aggregate photoconductive compositions coated on each ofthe three elements tested has an identical composition as indicated above except as shown in Table 4 hereinafter.

The evaluation of white light speed used in this example is carried out by subjecting each of the three aggregatephotoconductive compositions for equal times to an identical source of white light radiation using a lens system which is equivalent to a photographic f-number of f/l 1. Before the f/l 1 light exposure, each of the three compositions is given in the dark a uniform negative charge level of -500 volts. Accordingly. the composition which exhibits the highest white light speed in this test is the composition which most completely discharges to the zero charge level.

Each cycle of the 500 cycle electrical charge fatigue test carried out on these three aggregate elements comprises the steps of (a) subjecting the element to an initial uniform charge, V0, in the dark of -500 volts. imagewise exposing the uniformly negatively charged surface of the element to white light using a Xenon flashlamp to form an imagewise charge pattern on the surface of the element corresponding to the original light image pattern, and erasing the imagewise charge pattern by a uniform light exposure of the charge-bearing surface of the element. Since only the electrical properties of each element are being tested no development of the charge pattern or transfer thereof is carried out. After completing 500 repetitions of the foregoing cycle, the ability of the photoconductive element to accept completely the intitial charge, V0, of 500 volts is measured. If the element retains its ability to accept completely the -500 volt charge, no electrical fatigue is measurable; therefore the difference in initial charge acceptance capability, AVo as set forth in Table 4, is zero. If after completing the 500 repetitions of the fatigue test, the photoconductive element is no longer capable of completely accepting the full initial charge of -500 volts, the amount of charge it does accept is measured and the difference between this value and the initial 500 volts, i.e. AVo, is calculated and apperas under the column AVo in Table 4. As indicated in Table 4 an element containing an aggregate photoconductive composition which has only a conventional photoconductor known to be useful in aggregate photoconductive materials (i.e. bis(4-diethylamino)tetraphenyl methane) exhibits a AVo of 25 volts indicating that it definitely experiences significant electrical fatique when subjected to repeated re-charging and reexposure. This fatigue characteristic is, of course, disadvantageous for any such photoconductive element contemplated for use as a reusable photoconductive element. In contrast, as Table 4 clearly shows, when an amount of compound 11 of Table l is added to the aggregate photoconductive elements tested in this example, the amount of electrical fatigue as measured by the foregoing 500 cycle test is substantially reduced ultimately no measurable fatique is obtained as the amount of compound ll of Table 1 added to the aggregate photoconductive compositions tested in this example is in- Zll creased. However, as is also shown in Table l, the element which exhibits little or no measureable fatique also shows a white light speed loss relative to the elements containing lesser amounts of compound ll. Thus in accord with the invention, the amount of the distyryl-containing compound which should be added to obtain an optimum reusable aggregate photoconductive composition should be less than about 15 weight percent.

TABLE 4 ELECTRlCAL FATIGUE TEST RESULTS Remaining 40% by Weight of Aggregate Compositions Used in Elements of Example 3 Weight 71 of Weight 7: of fl] 1 Conventional Compound ll white light Photoconductor* of Table l AVo speed (volts) 40 (outside scope 25 -70 of present invention 0 l0 l 65 20 (outside scope 20 0 --2 l 5 of present invention) *hist J-dicth; lamino) tclraphcnylmcthunc selenapyrylium, and pyrylium dye salts and (ii) a car-' bonate polymer having an alkylidene diarylene moiety in a recurring unit, said discontinuous phase dispersed in said continuous phase, (c) at least one non-blue light absorbing organic photoconductor in solid solution with the continuous phase of said composition, and (d) from about 0.1 to about weight percent based on the dry weight of said composition of a compound having the formula R R R and R are each selected from the group consisting of an aryl radical and an alkyl radical, Ar, and Ar are each selected from the group consisting of an unsubstituted phenyl radical and a substituted phenyl radical having an alkyl, aryl, alkoxy, aryloxy, or halogen substituent, and Ar is an aromatic radical containing 4-14 carbon atoms in the aromatic ring thereof, said aromatic radical being a member selected from the group consisting of unsubstituted carbocyclic aromatic radicals, unsubstituted sulfur heterocyclic aromatic radicals having a sulfur atom as the only heteroatom thereof, and said carbocyclic or said sulfur heterocyclic aromatic radicals having an alkyl, aryl, alkoxy, aryloxy or halogen substituent.

2. A photoconductive composition as described in claim ll wherein said pyrylium salt has the formula:

wherein:

R and R are selected from the group consisting of phenyl and substituted phenyl having at least one substituent selected from the group consisting of an alkyl radical of from 1 to about 6 carbon atoms and an alkoxy radical of from 1 to about 6 carbon atoms;

R; is an alkylamino-substituted phenyl radical having from 1 to about 6 carbon atoms in the alkyl moiety;

X is selected from the group consisting of sulfur and oxygen; and

Z is an anion.

3. A photoconductive composition as described in claim .1 wherein said carbonate polymer contains the following moiety in a recurring unit:

wherein:

each of R and R when taken separately, is selected from the group consisting of a hydrogen atom, an alkyl radical of from 1 to about 10 carbon atoms, and a phenyl radical, and R and R when taken together, are the carbon atoms necessary to form a cyclic hydrocarbon radical, the total number of carbon atoms in R and R being up to 19; and

R and R are each selected from the group consisting of hydrogen, alkyl radicals of from 1 to about 5 carbon atoms, alkoxy radicals of from I to about 5 carbon atoms and a halogen atom.

4. An aggregate photoconductive composition comprising (a) a continuous electrically insulating carbonate polymer phase, said polymer having an alkylidene diarylene moiety in a recurring unit, (b) a discontinuous phase comprising a co-crystalline complex of (i) a 2,4,6-substituted thiapyrylium dye salt and (ii) a carbonate polymer having an alkylidene diarylene moiety in a recurring unit. said discontinuous phase dispersed in said continuous phase, (c) from about 25 to about weight percent based on the dry weight of said composition of at least one non-blue light absorbing organic photoconductor in solid solution with the continuous phase of said composition, and (d) from about 5 to about 10 weight percent based on the dry weight of said composition of a compound havin the formula wherein R R R and R are each selected from the group consisting of an aryl radical and an alkyl radical,

Ar, and Ar are each selected from the group consisting of an unsubstituted phenyl radical and a substituted phenyl radical having an alkyl, aryl, alkoxy, aryloxy, or halogen substituent, and

Ar is an unsubstituted carbocyclic aromatic radical containing 4-14 carbon atoms in the aromatic ring thereof or a substituted carbocyclic aromatic radical containing 4-14 carbon atoms in the aromatic ring thereof, said substituted aromatic radical having an alkyl, aryl, alkoxy, aryloxy, or halogen substituent, said compound in solid solution with the continuous phase of said composition.

5. An aggregate photoconductive composition as described in claim 4 wherein R R R and R are each phenyl radicals or alkyl-substituted phenyl radicals and Ar is a phenyl radical or an alkyl-substituted phenyl radical, said alkyl substituents having 1 or 2 carbon atoms.

6. An aggregate photoconductive composition as described in claim 4 wherein said compound is selected from the group consisting of 4-diphenylamino-4f-[4- diphenylamino)styryl]stilbene; 4-di-(p-tolylamino)-4'- [4-(di-p-tolylamino)styryl]stilbene; 4-di-ptolylamino)2, 3, 5, 6-tetramethyl-4-[4-(di-ptolylamino)styryl]stilbene; 4-di-(p-tolylamino)-2-[4- (di-p-tolylamino)styryl]stilbene; 4-di-(p-tolyla'mino)- 2,4-dimethyl-5-[4-(di-p-tolylamino)styryll-stilbene; and 1,4-bis(4-N-ethyl-N-p-tolylaminostyryl)benzene.

7. An aggregate photoconductive composition as described in claim 4 wherein said organic photoconductor is a polyarylalkane photoconductor or an arylamine photoconductor.

8. An aggregate photoconductive composition as described in claim 4 wherein said organic photoconductor is a polyarylalkane photoconductor.

9. In an electrophotographic element comprising a conductive support and a photoconductive layer coated over said support, the improvement wherein said photoconductive layer comprises the photoconductive composition of claim 1.

10. In an electrophotographic element comprising a conductive support and a photoconductive layer coated over said support, the improvement wherein said photoconductive layer comprises the photoconductive composition of claim 4.

11. In an electrophotographic process wherein an electrostatic charge pattern is formed on a photocon ductive element comprised of an electrically conducting support having coated thereover a layer of a photoconductive composition, the improvement wherein said photoconductive composition is a composition as described in claim 4.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3, 73,3 DATED March 25, 1975 INVENTOR(S) 1 Lawrence E. Contois and Louis J. Rossi It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 5%, "these" should read --These--.

Column t, line 37, interest" should read --interact; line 58, aromataic" should read -'---aromatic--.

Column 5, line 65, "bromopenetyl" should read ---bromopentyl--.

Column 6, line 20, after "phenoxyphenyl," --naphthoXyphenyl,-- should be inserted; line 25, after "hydroxynaphthyl,", ---hydroxyanthryl, etc.- should be added; line 33, that part of formula reading "etehylaminoghenyl" should read ---ethylaminophenyl---; lines 3 -39, "chloroanphthyl" should read ---chloronaphthyl; line 50, after "including", --substituted--- should be inserted.

Column 7, line 56, "below" should read --belong-.

Column 8, line 6 "this" should read --This-.

Column 9, line 19, oroganic" should read --organic-. Column 10, line 22, "abe should read ---be---; line 22, sulfer" should read --sulfur--; line 53, "hydrogen" should read ---hydrocarbon---.

Column 11, line 29, "3,1o6, r r r" should read ---3,1o6,5 r r---.

Column 12, line 15, that part of formula reading "poly IA should read ---poly IA line 33, "polyers" should read ---polymers--; line 3 before "physical", ---alter--- should be inserted; line 37, "polyers" should read -polymers---.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,873,3 g 2 D TE March 25, 1975 r rg) Lawrence E. Contois and Louis J. Rossi It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

(continued) Column 13, lines FO- L1, "absorportion should read ---absorption---.

Column 15, line 51, "distytyl-corltaining" should read ---distyrylcontaining-.

Column 18, lines 21-22, that part of formula reading t,- tbis" should read t, t' -bis---.

Column 20, line #9, ,"apperas" should read ---appears---.

Column 23, line 27, that part of formula reading "tolylamino)2' ,3 ,5,6'" should read ---tolylamino)-2' ,3, 5'.6-.

Signed and Sealed this sixth D y of January 1976 [SEAL] A ttes t:

RUTH C. MASON C. MARSHALL DANN Anesn'ng Officer Commissioner ofParerrrs and Trademarks 

1. AN AGGREGATE PHOTOCONDUTIVE COMPOSITION COMPRISING (A) A CONTINUOUS ELECTRICALLY INSULATING POLYMER PHASE, SAID POLYMER HAVING AN ALKYLIDENE DIARRYLENE MOIETY IN A RECURRING UNIT, (B) A DISCONTINUOUS PHASE COMPRISING A CO-CRYSTALLINE COMPLEX OF (I) A PYRYLIUM SALT SELECTED FROM THE GROUP CONSISTING OF THIAPYRYLIUM, SELENAPYRYLIUM, AND PYRYLIUM DYE SALTS AND (II) A CARBONATE POLYMER HAVING AN ALKYLIDENE DIARRYLENE MOIETY IN A RECURRING UNIT, SAID DISCONTINUOUS PHASE DISPERSED IN SAID CONTINUOUS PHASE, (C) AT LEAST ONE NON-BLUE LIGHT ABSOBING ORGANIC PHOTOCONDUCTOR IN SOLID SOLUTION WITH THE CONTINUOUS PHASE OF SAID COMPOSITION, AND (D) FROM ABOUT 0.1 TO ABOUT 15 WEIGHT PERCENT BASED ON THE DRY WEIGHT OF SAID COMPOSITION OF A COMPOUND HAVING THE FORMULA
 2. A photoconductive composition as described in claim 1 wherein said pyrylium salt has the formula:
 3. A photoconductive composition as described in claim 1 wherein said carbonate polymer contains the following moiety in a recurring unit:
 4. An aggregate photoconductive composition comprising (a) a continuous electrically insulating carbonate polymer phase, said polymer having an alkylidene diarylene moiety in a recurring unit, (b) a discontinuous phase comprising a co-crystalline complex of (i) a 2,4,6-substituted thiapyrylium dye salt and (ii) a carbonate polymer having an alkylidene diarylene moiety in a recurring unit, said discontinuous phase dispersed in said continuous phase, (c) from about 25 to about 40 weight percent based on the dry weight of said composition of at least one non-blue light absorbing organic photoconductor in solid solution with the continuous phase of said composition, and (d) from about 5 to about 10 weight percent based on the dry weight of said composition of a compound having the formula
 5. An aggregate photoconductive composition as described in claim 4 wherein R1, R2, R3, and R4 are each phenyl radicals or alkyl-substituted phenyl radicals and Ar2 is a phenyl radical or an alkyl-substituted phenyl radical, said alkyl substituents having 1 or 2 carbon atoms.
 6. An aggregate photoconductive composition as described in claim 4 wherein said compound is selected from the group consisting of 4-diphenylamino-4''-(4-diphenylamino)styryl)stilbene; 4-di-(p-tolylamino)-4''-(4-(di-p-tolylamino)styryl)stilbene; 4-di-p-tolylamino)2'', 3'', 5'', 6''-tetramethyl-4''-(4-(di-p-tolylamino)styryl)stilbene; 4-di-(p-tolylamino)-2''-(4-(di-p-tolylamino)styryl)stilbene; 4-di-(p-tolylamino)-2'',4''-dimethyl-5''-(4-(di-p-tolylamino)styryl)-stilbene; and 1,4-bis(4-N-ethyl-N-p-tolylaminostyryl)benzene.
 7. An aggregate photoconductive composition as described in claim 4 wherein said organic photoconductor is a polyarylalkane photoconductor or an arylamine photoconductor.
 8. An aggregate photoconductive composition as described in claim 4 wherein said organic photoconductor is a polyarylalkane photoconductor.
 9. In an electrophotographic element comprising a conductive support and a photoconductive layer coated over said support, the improvement wherein said photoconductive layer comprises the photoconductive composition of claim
 1. 10. In an electrophotographic element comprising a conductive support and a photoconductive layer coated over said support, the improvement wherein said photoconductive layer comprises the photoconductive composition of claim
 4. 11. In an electrophotographic process wherein an electrostatic charge pattern is formed on a photoconductive element comprised of an electrically conducting support having coated thereover a layer of a photoconductive composition, the improvement wherein said photoconductive composition is a composition as described in claim
 4. 